Is a private collection in a class, thread safe? RSS

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  boeledi

  Member

  38 Points

  26 Posts

  Is a private collection in a class, thread safe?

  Feb 09, 2013 02:12 PM|LINK

  Hi,

  Is a private collection in an instance of a class, threadsafe?

  In order to illustrate my question, please have a look at the following "stupid" code.

  As you will see "myClass" instantiates a "private" collection.

  "anotherClass" instantiates "myClass" and populates the collection, then passes the instance of "myClass" to a shared method of another class "aThirdClass", which in turn "gets" and "sets" the contents of the collection.

  So, the question, is this code ThreadSafe or do I systematically have to use the SyncLock, each time I need to get access to the contents of the hashTable?

  Public Class myClass
  	Private _myCollection As HashTable = New HashTable(StringComparer.OrdinalIgnoreCase)
  
  	Public Sub AddValue(ByVal key As String, ByVal value As String)
  		If (Not _myCollection.ContainsKey(key)) Then
  			_myCollection.Add(key, value)
  		End If
  	End Sub
  
  	Public Function GetValue(ByVal key As String) As String
  		Dim strValue As String = String.Empty
  		If (_myCollection.ContainsKey(key)) Then
  			strValue = _myCollection(key)
  		End If
  		Return strValue
  	End Function
  End Class
  
  Public Class anotherClass
  	Public Shared Sub myRoutine()
  		Dim anInstance As myClass = New myClass()

                  
  		anInstance.AddValue("key1", "value1")
  		anInstance.AddValue("key2", "value2")
  
  		aThirdClass.DoSomething(anInstance)
  
  		If (Not String.IsNullOrEmpty(anInstance.getValue("key3")) Then

  		End If
  	End Sub
  End Class
  
  Public Class aThirdClass
  	Public Shared Sub DoSomething(ByVal theInstance As myClass)
  		Dim strValue As String = theInstance.GetValue("key2")
  		theInstance.AddValue("key3", "value3")
  	End Sub
  End Class
  
  

  Many thanks for your feedback
  
  

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  dahla

  Participant

  1816 Points

  369 Posts

  Re: Is a private collection in a class, thread safe?

  Feb 10, 2013 02:37 AM|LINK

  Try reading this article http://msdn.microsoft.com/en-us/library/system.collections.hashtable.aspx

  Using a hashtable that is a threadsafe as you can get, like described in the article, without adding some kind of synchronization

  • Marked as answer by Amy Peng - MSFT on Feb 18, 2013 09:23 AM